Streaming



Oct. 13, 1970 J BLAKELY ETAL 36,533,562

STREAMING mm June 3, 1968 United States Patent 3,533,562 STREAMING James Madison Blakely, Los Angeles, and Nathaniel Hughes, Beverly Hills, Califi, assignors to Energy Sciences, Inc., El Segundo, Calif., a corporation of California Filed June 3, 1968, Ser. No. 733,895 Int. Cl. B05b 1/14 US. Cl. 239-553.5 6 Claims ABSTRACT OF THE DISCLOSURE Streaming to supersonic speeds with small nozzles using boundary layer to define effective nozzle surfaces and constructed of simple parts.

This invention relates to streaming at supersonic speeds using small nozzles in which effective nozzle surfaces are defined by boundary layer effects, and represents an improvement on the subject matter of the pending application of Nathaniel Hughes, S.N. 718,447, filed Apr. 3, 1968, Supersonic Streaming, the contents of which are hereby incorporated by reference herein.

An object of the invention is to make possible inexpensive manufacture of nozzles embodying the invention of said Hughes application, and to minimize the variety of parts required for inventory. A further important object is to provide improved heat transfer into the nozzle.

In general, the invention features providing a housing with an inner surface round in cross-section in which is disposed a body having an interrupted mating outer surface, the latter including a circumferential interruption to form with the housing a manifold and opposed longitudinal interruptions to provide with the housing passageways to the manifold. In preferred embodiments, both parts are formed of a good heat conductor, such as brass.

Other objects, features, and advantages will appear from the following description of a preferred embodiment of the invention, taken in conjunction with the drawings, in which:

FIG. 1 is a perspective view, partially in section, from a first point of view, of said preferred embodiment;

FIG. 2 is a perspective sectional view, taken at 2-2 of FIG. 1, from a second point of view of said embodiment; and

FIG. 3 is a sectional view, taken at 3-3 of FIG. 1.

Referring now to the drawings, there is shown in FIG. 1 a nozzle unit indicated generally at 10, and including a housing 12 and a body 14.

Both housing 12 and body 14 are formed of freemachining brass, and the interrupted cylindrical outer surface of the latter press-fittedly engages the cylindrical inner surface of the former.

The housing 12 bears threads 16 for use in connecting the device in line with a source of air pressure and 0pposed parallel flat surfaces 18 to facilitate application of a wrench to the device.

Body 14 includes inlet portion 20 including, coaxial with said body, nozzle feed hole 22 and inlet hole 24, the downstream end of the latter lying in the nozzle inlet plane. Downstream of said plane, the body 14 includes boundary layer confining wall 26. The outer surface of body 14 is circumferentially relieved over most of said confining wall 26, but not at the downstream extremity thereof, which is left unrelieved to form circumferential housing-engaging ring 28. Four holes 30 with centerlines spaced 90 and all lying in the same plane perpendicular to the body 14 axis extend through confining wall 26.

The wall 26 defines with the inner surface of housing 12 and with the ring 28 a manifold 32 fed through the Patented Oct. 13, 1970 zones defined between flats 34 of the inlet portion 20 and the housing 12 inner surface.

Two symmetrical circle segments, defined by flats 34 of inlet portion 20 and the inner surface of wall 26, lie in the plane (perpendicular to the body 14 axis) at the upstream end of wall 26.

Wall portion 26 terminates at its downstream inner surface in 45 countersink 38.

The inner surface of wall 26 and inlet hole 24 are concentric to within 0.001 inch.

In operation, air at a low pressure is introduced into the housing 12 at its threaded upstream end. Part of the air then passes through nozzle feed hole 22 and nozzle inlet hole 24 into the nozzle proper, which is defined by boundary layer confining wall 26. Another part of the air moves through the two zones, segments of circles in transverse cross-section, alongside the parallel and opposed flats 34, to be divided then by the wall 26. Part of the air passes through the two symmetrical circle segments 36 into the nozzle, to enhance boundary layer flow and energy and the work done by the outlet shocks. The remainder moves outside wall 26 into manifold 32 and thence through holes 30.

The low air inlet pressure and the small nozzle diameter cooperate to produce a rapid buildup in boundary layer thickness downstream of each nozzle inlet, with a consequent rapid diminution of effective diameter for air streaming; i.e., in every practical respect, to form a converging nozzle portion sculptured in boundary layer. The boundary layer becomes at about the plane in which lie the axes of holes 30, of such thickness that the effective diameter for air flow is D* (flow occurs in the boundary layer too, of course, but much more slowly, and for purposes of calculating D*, the boundary layer may be treated as though motionless), the diameter at which effective air flow rate therethrough is such that the ratio of inlet pressure to throat plane pressure (P /P is that characteristic of transition from subsonic to supersonic flow (i.e., transonic).

Injection of air through holes 30 (which for balance should be in opposed pairs) stabilizes D* axially, as well as affecting it absolutely (since the greater the rate of flow through holes 30, the smaller D* tends to be, the fluid coming in through holes 30, supplementing the boundary layer growth effects). Injecting at the throat plane using a source of pressure common with that to the nozzle inlet (P has the additional important advantage that the eflect of line pressure fluctuations is minimized. If line pressure I, changes, D* varies to ad just for the resulting change in c.f.m. flow rate, thus giving much greater flow rate variation tolerance without loss of supersonic character.

In designing a nozzle, the desired power (the product of nozzle inlet pressure P, and flow rate V, often expressed in cubic feet per minute c.f.m.) is first chosen by fixing P and V to give the desired P V. The desired jet outlet pressure P is then selected. Using standard thermodynamic One-Dimensional Isentropic Compressible Flow Functions tables, the matching ratio of effective nozzle outlet area (A to effective throat area (A*) is selected. Nozzle length from inlet plane to holes 30 centerline plane L* and overall length L downstream of the inlet plane are then selected to give the appropriate, owing to boundary layer growth and decay for the nozzle inside diameter D, chosen, effective throat diameter D* and outlet diameter D In the preferred embodiment, the parameters are: P,--1 p.s.i.g.

V-2.23 c.f.m. P -1.0 p.s.i.a. L*0.152 inch L-O.255 inch D 0.lO3 inch Hole 30 diameter0.062 inch Hole 24 diameter-0.076 inch Hole 24 length0.025 inch The resultant supersonic jet is useful for many purposes, e.g., atomization.

The nozzle device of this invention is particularly wellsuited to use in aerosol spray devices. In such devices the improved heat transfer incident to film scrubbing owing to movement of air along the outer surface of wall 26 facilitates discharge of a spray not cold to the touch even though a Freon propellant is used.

The simple two-piece nozzle unit of this invention may be manufactured simply, using standard screw-manufacturing machinery. The body portions may be stocked as blanks without drilling holes 30, so that by varying those different effective nozzles may be made up from the same items of inventory. The same housing may be used with various bodies.

Provision of forced subsonic implosion from the air source through the segment-in-cross-section passages alongside flats 34 and at 36 greatly increases the energy of the boundary layer and the force of the supersonic implosion into the emerging supersonic jet. The subject matter of this paragraph is the sole invention of Nathaniel Hughes, joint inventor of the invention of this application.

Other embodiments will occur to those skilled in the art and are within the following claims.

What is claimed is:

1. A supersonic nozzle comprising:

a housing having an inner cylindrical surface; and,

a body mounted within said housing and having an interrupted outer surface comprising;

axially-spaced surface portions defined by a cylinder of diameter equal to the diameter of said housing inner surface and engaging said inner surface and, therebetween, an intermediate surface portion defining, in cooperation with said inner surface, a circumferential manifold, and, in cooperation with an inner surface of said body, a nozzle boundary layer confining wall, and

opposed longitudinal interruptions extending from a first end of said body to said manifold to provide in cooperation with said inner surface, passageways along said body from said body from said first end to said manifold, and

said body including a cavity defined at least in part by said inner surface of said body, and

holes extending through said wall to provide communication between said manifold and said cavity for nozzle throat plane stabilization.

2. The nozzle of claim 1 in which said intermediate surface portion and said body inner surface are defined, respectively, by concentric cylinders of diameter less than the diameter of said housing inner surface.

3. The nozzle of claim 1 in which each said longitudinal interruption defines with said inner surface, in cross section, a segment of a circle.

4. The nozzle of claim 1 in which each said longitudinal interruption extends also to said cavity to provide a passageway along said body from said first end to said cavity.

5. The nozzle of claim 1 in which said body is formed from metal.

6. The nozzle of claim 1 in which said housing and said body are formed from a material selected from the class consisting of copper and alloys containing copper.

References Cited FOREIGN PATENTS 1,197,685 6/1959 France.

LLOYD L. KING, Primary Examiner US. Cl. X.R. 

